The present invention relates to germinated brown rice having good safety and cooking properties, a process for producing the same, and a processed food prepared therefrom.
Brown rice (i.e., unpolished or unmilled rice) is highly nutritious compared to white rice (i.e., polished or milled rice). Brown rice contains most of the nutrients necessary for a living human body, particularly rich in dietary fibers, B vitamins and vitamin E whose physiological functions have recently become the focus of attention.
Although brown rice is an excellent food material as mentioned above, its surface is surrounded by a tough outer layer rich in oils and fibrous ingredients, which prevents penetration of heat and absorption of water upon cooking under ambient pressure, resulting in insufficient starch gelatinization and insufficient softening/decomposition of the outer layer tissue.
Therefore, brown rice cooked under ambient pressure is harder and less sticky and has a poorer eating quality (i.e., palatability) compared to cooked white rice.
In order to overcome these disadvantages, brown rice has been cooked under pressure. However, in the cooking under pressure, a part of high temperature/high pressure-sensitive nutrients in brown rice (e.g., vitamins) is decomposed. Moreover, when brown rice is heated until its outer layer becomes sufficiently soft, the region other than the outer layer becomes mushy due to gelatinization of starch. Therefore, it is almost impossible to cook brown rice into cooked rice that is smooth to eat and has good digestion/absorption properties.
It is known that brown rice may be immersed in warmed water of 5-50xc2x0 C., preferably 20-40xc2x0 C., for an appropriate period of time to cause the germination of the brown rice and the germinated brown rice may then be boiled or steamed under ambient pressure, whereby softly cooked brown rice can be prepared.
As used herein, the term xe2x80x9cgerminationxe2x80x9d or xe2x80x9cgerminatingxe2x80x9d means that brown rice is germinated to such an extent that a bud is grown from the embryo, and preferably a bud of about 0.5 to about 1 mm can be observed by the naked eye. This term also encompasses the state of brown rice where no bud is observed but the embryo is expanded, namely xe2x80x9cpre-germinationxe2x80x9d state.
When brown rice is germinated in this manner, however, it changes into a fermented state during the germination process by the metabolic action of the brown rice itself or due to the proliferation of undesirable microorganisms on the outer surface of the brown rice or in water into which the brown rice is immersed. As a result, a fermentation odor or other unpleasant odor is generated and remains in the germinated brown rice after the heat treatment.
Moreover, in such germinated brown rice, there is also a problem that the decomposition of starch or the like progresses excessively by the action of the endogenous enzymes with the passage of time, resulting in deterioration in quality as a food material.
In order to overcome the above-mentioned disadvantages, many methods have been proposed, in which brown rice is germinated in hot water containing a bactericidal agent or in a dilute electrolytic saline, germinated in running water, or germinated in hot water while replacing the water with fresh water at regular intervals.
However, when employing a chemical, there is the concern over the influence of residual chemical on the germinated brown rice or a chemical odor remaining on the germinated brown rice; while in the case of a method utilizing hot water that is replaced with fresh water at regular intervals or a method utilizing running water, the production process is water- and energy-wasting and is complicate to control.
An object of the present invention is to provide germinated brown rice safely, with a low contamination by microorganisms and without fermentation odor or any other unpleasant odors. Another object of the present invention is to provide a process for producing germinated brown rice efficiently. Still another object of the present invention is to provide a processed food prepared from the germinated brown rice which is good to the taste and highly nutritious.
The present inventors have studied for achieving the aforementioned objects. As a result, the inventors have found that germinated brown rice capable of being processed into soft, sticky and highly nutritious cooked brown rice can be produced by treating germinated brown rice with hot water or steam. This finding led to the accomplishment of the present invention.
According to the first aspect of the present invention, there is provided germinated brown rice having a degree of starch gelatinization of from 30 to 90%, a water content of from 20 to 70%, an xcex1-amylase activity of not greater than 5 IU/g, and a population of attached microorganisms of not greater than 10,000/g.
According to the second aspect of the present invention, there is provided germinated brown rice having a degree of starch gelatinization of from 30 to 90%, a water content of from 20 to 70%, an xcex1-amylase activity of not greater than 2 IU/g, a population of attached microorganisms of not greater than 1,000/g, and an ethyl alcohol content of from 0.5 to 20%.
According to the third aspect of the present invention, there is provided a process for producing the germinated brown rice according to the first aspect of the present invention, comprising treating germinated brown rice with hot water or steam.
According to the fourth aspect of the present invention, there is provided a process for producing the germinated brown rice according to the second aspect of the present invention, comprising treating germinated brown rice with hot water or steam, and then adding ethyl alcohol to the treated germinated brown rice.
In the third or fourth aspect of the present invention, the treatment of the germinated brown rice with hot water may be performed by immersing the germinated brown rice in hot water of 60 to 100xc2x0 C. for 5 to 30 minutes.
In the third or fourth aspect of the present invention, the treatment of the germinated brown rice with steam may be performed by steaming with steam of 0.5 to 1.5 kg/cm2 for 5 to 30 minutes.
According to the fifth aspect of the present invention, there is provided a processed food prepared by processing the germinated brown rice according to the first or second aspect of the present invention.
This specification includes part or all of the contents as disclosed in the specification of Japanese Patent Application No.24694/1999, which is a priority document of the present application and incorporated herein by reference in its entirety.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof.
The present invention is described in detail in the following.
The germinated brown rice according to one aspect of the present invention has characteristics of a degree of starch gelatinization of from 30 to 90%, a water content of from 20 to 70%, an xcex1-amylase activity of not greater than 5 IU/g, and a population of attached microorganisms of not greater than 10,000/g. The germinated brown rice preferably has characteristics of a degree of starch gelatinization of from 50 to 85%, a water content of from 25 to 40%, an xcex1-amylase activity of not greater than 2 IU/g and a population of attached microorganisms of not greater than 500/g. The microorganisms attached onto the germinated brown rice include general bacteria (e.g., Escherichia coli, Bacillus subtilis), ray fungus (e.g., Streptomyces) and fungi (e.g., Penicillium).
The germinated brown rice according to another aspect of the present invention has characteristics of a degree of starch gelatinization of from 30 to 90%, a water content of from 20 to 70%, an xcex1-amylase activity of not greater than 2 IU/g, a population of attached microorganisms of not greater than 1,000/g, and an ethyl alcohol content of from 0.5 to 20%.
The germinated brown rice may be prepared by treating brown rice that has been germinated in a conventional manner, with hot water or steam.
The treatment of germinated brown rice with hot water may be performed by immersing the germinated brown rice in hot water of 60 to 100xc2x0 C., preferably 90 to 100xc2x0 C., for 5 to 30 minutes, preferably for 5 to 10 minutes.
In the treatment with hot water, if the temperature of the hot water used is lower than 60xc2x0 C. or the time of immersing the germinated brown rice in hot water is shorter than 5 minutes, then the deactivation of endogenous enzymes is insufficient and the satisfactory reduction in population of attached microorganisms cannot be achieved.
If the temperature of the hot water is too high or the time of immersing the germinated brown rice in hot water is too long, although the population of attached microorganisms can be reduced satisfactorily, the gelatinization of starch progresses excessively and, as a result, the shape of the germinated brown rice cannot be retained and the stickiness of the surface layer of the germinated brown rice becomes too high. Therefore, these conditions are not preferable.
The treatment of germinated brown rice with steam may be performed by treating the germinated brown rice with steam of 0.5 to 1.5 kg/cm2 generated with a boiler or the like for 5 to 30 minutes, preferably for 10 to 20 minutes.
In the treatment with steam, if the time of treatment is too short, then the satisfactory reduction in population of attached microorganisms cannot be achieved, whereas if the time is too long, then the shape of the germinated brown rice cannot be retained and the stickiness of the germinated brown rice becomes too high. Therefore, these conditions are not also preferable.
The germinated brown rice containing ethyl alcohol may be prepared by treating germinated brown rice with hot water or steam and then adding ethyl alcohol thereto. The ethyl alcohol may be absolute or aqueous ethyl alcohol. The ethyl alcohol may be added to the germinated brown rice in an appropriate amount by spraying or the like, thereby to cause the absorption of ethyl alcohol by the germinated brown rice.
The processed food prepared from the germinated brown rice of the present invention includes, for example, rice snacks (e.g., rice crackers), breads, noodles or pastas (e.g., bean threads). These food products can be produced by adding an appropriate amount of the per-germinated brown rice in the corresponding production processes.
The germinated brown rice of the present invention undergoes less degradation in quality caused by the proliferation of microorganisms during the distribution process of the germinated brown rice. The germinated brown rice can be cooked readily under ordinary pressure, thereby producing cooked brown rice that is soft, sticky, good to the taste and rich in nutrients.
In contrast, germinated brown rice without treatment with hot water or steam as described above is metabolically active and, as a result, exhibits high activities of hydrolases such as xcex1-amylase. In such germinated brown rice, starch and proteins are decomposed and plumules and radicles grow excessively with the passage of time, and therefore such germinated brown rice becomes unsuitable to eat.
Hereinbelow, the present invention will be illustrated in more detail with reference to the following examples. It should be understood, however, that the invention is not limited to the examples.